Where flies drive loons off nests, DNR analyzes eggs

A loon sits in a nest along the shore of Sagatagan Lake near St. John's University in Collegeville in 2010 An effort is under way to abandoned nests in the region for signs of contamination.
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Times photo by Jason Wachter
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The recent emergence of black flies has prompted the Minnesota Department of Natural Resources to ask for loon-watchers' help.

Carrol Henderson, the DNR's nongame wildlife supervisor, said a heavy black fly hatch several years ago forced some incubating loons to abandon their nests. The top of the loons' heads looked as if they were covered in Velcro in one photograph he received.

"It appears through a portion of north-central Minnesota we've got a similar occurrence this year, and it apparently extends all the way to north central Wisconsin," Henderson said.

While some loons may renest later in the season, Henderson said the DNR wants to salvage any abandoned eggs for chemical analysis to determine if they contain petroleum contaminants transmitted by the adults nesting in the Gulf of Mexico waters affected by the Deepwater Horizon oil spill.

The DNR received $260,000, available July 1, to continue the second phase of assessing the potential affect of contaminants on loons and pelicans in Minnesota. That study also will use radiotelemetery and geolocators.

Kevin Woizeschke, the Brainerd-based nongame wildlife specialist, said he started to hear reports of black flies last week.

The flies bite loons' eyelids and nostrils, forcing them to dive repeatedly. Some are eventually forced off the nest. Henderson said 23 eggs were turned in for analysis last year.